Piezoelectric semiconductor
| Title: | Piezoelectric semiconductor |
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| Patent Number: | 5,393,444 |
| Publication Date: | February 28, 1995 |
| Appl. No: | 08/112,529 |
| Application Filed: | August 27, 1993 |
| Abstract: | A piezoelectric semiconductor is a single crystal composed mainly of ZnO having properties such as electrical conductivity of 10.sup.-11 .about.10.sup.-3 1/.OMEGA..multidot.cm suitable for use as an acoustoelectric element, by adding a given amount of H.sub.2 O.sub.2 to the alkali solvent, or by using NH.sub.4 OH in the alkali solvent, or by doping the ZnO single crystal with Li or a trivalent metal. The piezoelectric semiconductor can be suitably used as a ultrasonic transducer material of acoustoelectric type and can also be used as a material for ultrasonic amplification, an surface acoustic wave filter, a piezoelectric transducer, a fluorescent material for emitting a low-velocity electron beam, etc. |
| Inventors: | Asai, Yuji (Chita, JPX); Imai, Osamu (Kasugai, JPX) |
| Assignees: | NGK Insulators, Ltd. (Nagoya, JPX) |
| Claim: | What is claimed is |
| Claim: | 1. A piezoelectric semiconductor for use as an acoustoelectric element comprising a single crystal composed mainly of ZnO, said single crystal having an electrical conductivity of 10.sup.-11 .about.10.sup.-6 1/.OMEGA..multidot.cm, a carrier mobility of at least 30 cm.sup.2 /V.multidot.sec, and a variation in electrical conductivity in said single crystal of 10.sup.2 1/.OMEGA..multidot.cm or smaller. |
| Claim: | 2. The piezoelectric semiconductor of claim 1, wherein said carrier mobility is at least 60 cm.sup.2 /V.multidot.sec. |
| Claim: | 3. A piezoelectric semiconductor for use as an acoustoelectric element comprising a single crystal composed mainly of ZnO, said single crystal having an electrical conductivity of 10.sup.-6 .about.10.sup.-3 1/.OMEGA..multidot.cm, a carrier mobility of at least 30 cm.sup.2 /V.multidot.sec, and a variation in electrical conductivity in said single crystal of 10.sup.2 1/.OMEGA..multidot.cm or smaller. |
| Claim: | 4. The piezoelectric semiconductor of claim 3, wherein the electrical conductivity is 10.sup.-5 .about.10.sup.-4 1/.OMEGA..multidot.cm. |
| Claim: | 5. The piezoelectric semiconductor of claim 3, wherein said single crystal is doped with 15-120 ppm of Li. |
| Claim: | 6. The piezoelectric semiconductor of claim 3, wherein said single crystal is doped with 5-120 ppm of a trivalent metal. |
| Claim: | 7. The piezoelectric semiconductor of claim 6, wherein the trivalent metal is selected from the group consisting of Al and In. |
| Claim: | 8. The piezoelectric semiconductor of claim 3, wherein said carrier mobility is at least 60 cm.sup.2 V.multidot.sec. |
| Current U.S. Class: | 252/623ZT; 252/629; 423/622 |
| Current International Class: | H01L 4118 |
| Other References: | "Hydrothermal Growth and Stoichiometric Assessment of ZnO Single Crystals of High Purity," Noboru Sakagami, Res. Rep. of Akita National College of Technology 23 (1988) pp. 25-29, no month. "The Hydrothermal Growth of Low Carrier Concentration ZnO at High Water and Hydrogen Pressures," E. D. Kolb, A. S. Coriell, R. A. Laudise and A. R. Hutson (Bell Telephone Lab), Mat. Res. Bull. 2 (1967) pp. 1099-1106, no month. "Hydrothermal Growth of Large Sound Crystals of Zinc Oxide," R. A. Laudise, E. D. Kolb, A. J. Caporaso (Bell Telephone Lab), J. Amer. Ceram. Soc. 46 (1964) pp. 9-12, no month. |
| Primary Examiner: | Cooper, Jack |
| Attorney, Agent or Firm: | Adduci, Mastriani, Schaumberg & Schill |
| Accession Number: | edspgr.05393444 |
| Database: | USPTO Patent Grants |
| Language: | English |
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